1) Acid-Base Balance Flashcards
What is normal range for pH in the blood?
7.35-7.45
What are the clinical effects of alkalaemia?
Lowers free calcium therefore paraesthesia and tetany
What are the clinical effects of acidemia?
Hyperkalemia - arrhythmia
Denatures proteins - affects glycolysis, hepatic function, muscle contractility
What system allows pH to be maintained in a small range?
CO2/HCO3- buffer system
Describe how ventilation can affect acid base balance:
Hyperventilation -> hypocapnia -> rise in pH
Hypoventilation -> hypercapnia -> fall in pH
Explain the cellular mechanisms of H+ excretion in the distal tubule:
Active secretion - buffered by ammonia and phosphate
Explain the cellular mechanisms of re-absorption of HCO3- in the proximal tubule:
Na+/H+ exchanger causes H+ to move into lumen where is reacts with HCO3- to form CO2 and re-enter cell. Converted back to HCO3- which enters ECF
Describe the interactions between acid base status and plasma [K+]:
Acidosis -> hyperkalemia
Alkalosis -> hypokalemia
What conditions can lead to respiratory acidosis?
COPD
Severe asthma
Drug overdose
Neuromuscular disease
What conditions can lead to respiratory alkalosis?
Panic attacks
Hyperventilation in response to long term hypoxia
What conditions can lead to metabolic acidosis?
Diabetic ketoacidosis
Lactic acidosis
Uraemic acidosis - advanced renal failure
What conditions can lead to metabolic acidosis with a normal anion gap?
Renal tubular acidosis
Severe persistent diarrhoea
What conditions can lead to metabolic alkalosis?
Severe prolonged vomiting
Potassium depletion
Diuretics - loop and thiazide
When can metabolic alkalosis be a particular problem?
Volume depletion
